Nebraska Administrative Code
Topic - HEALTH AND HUMAN SERVICES SYSTEM
Title 179 - PUBLIC WATER SYSTEMS
Chapter 16 - DISINFECTANTS AND DISINFECTION BYPRODUCTS
Section 179-16-005 - MONITORING REQUIREMENTS

Universal Citation: 179 NE Admin Rules and Regs ch 16 ยง 005

Current through March 20, 2024

005.01 General Requirements

1. Systems must take all samples during normal operating conditions.

2. Systems may consider multiple wells drawing water from a single aquifer as one treatment plant for determining the minimum number of TTHM and HAA5 samples required, with Department approval.

3. Failure to monitor in accordance with the monitoring plan required under 179 NAC 16-005.06 is a monitoring violation.

4. Failure to monitor will be treated as a violation for the entire period covered by the annual average where compliance is based on a running annual average of monthly or quarterly samples or averages and the system's failure to monitor makes it impossible to determine compliance with MCLs or MRDLs.

5. Systems may use only data collected under the provisions of 179 NAC 16 to qualify for reduced monitoring.

005.02 Monitoring Requirements for Disinfection Byproducts

1. Total Trihalomethanes (THMs) and HAA5
a. Routine Monitoring: Systems must monitor at the frequency indicated in the following table:

ROUTINE MONITORING FREQUENCY FOR TTHM AND HAA5

Type of System

Minimum Monitoring Frequency

Sample Location in the Distribution System

Public water system using surface water or ground water under the direct influence of surface water serving at least 10,000 individuals

Four water samples per quarter per treatment plant

At least 25% of all samples collected each quarter at locations representing maximum residence time. Remaining samples taken at locations representative of at least average residence time in the distribution system and representing the entire distribution system, taking into account number of individuals served, different sources of water, and different treatment methods.1

Public water system using surface water or ground water under the direct influence of surface water serving from 500 to 9,999 individuals

One water sample per quarter per treatment plant

Locations representing maximum residence time1

Public water system using surface water or ground water under the direct influence of surface water serving fewer than 500 individuals

One sample per year per treatment plant during month of warmest water temperature

Locations representing maximum residence time.1 If the sample (or average of annual samples, if more than one sample is taken) exceeds the MCL, the system must increase monitoring to one sample per treatment plant per quarter, taken at a point reflecting the maximum residence time in the distribution system, until the system meets criteria in 179 NAC 16-005.02 item 1.d.

System using only ground water not under direct influence of surface water using chemical disinfectant and serving at least 10,000 individuals

One water sample per quarter per treatment plant2

Locations representing maximum residence time1

System using only ground water not under direct influence of surface water using chemical disinfectant and serving fewer than 10,000 individuals

One sample per year per treatment plant2 during month of warmest water temperature

Locations representing maximum residence time.1 If the sample (or average of annual samples, if more than one sample is taken) exceeds the MCL, the system must increase monitoring to one sample per treatment plant per quarter, taken at a point reflecting the maximum residence time in the distribution system, until the system meets criteria in 179 NAC 16-005.02 item 1.d.

1 If a system elects to sample more frequently than the minimum required, at least 25% of all samples collected each quarter (including those taken in excess of the required frequency) must be taken at locations that represent the maximum residence time of the water in the distribution system. The remaining samples must be taken at locations representative of at least average residence time in the distribution system.

2 Multiple wells drawing water from a single aquifer may be considered one treatment plant for determining the minimum number of samples required, with Department approval.

b. Systems may reduce monitoring, except as otherwise provided, in accordance with the following table:

REDUCED MONITORING FREQUENCY FOR TTHM AND HAA5

If You Are a . . .

You May Reduce

Monitoring If You Have

Monitored At Least One

Year and Your . . .

To This Level

Public water system using surface water or ground water under the direct influence of surface water serving at least 10,000 individuals which has a source water annual average TOC level, before any treatment, <= 4.0 mg/L

TTHM annual average <= 0.040 mg/L and HAA5 annual average <= 0.030 mg/L

One sample per treatment plant per quarter at distribution system location reflecting maximum residence time

Public water system using surface water or ground water under the direct influence of surface water serving from 500 to 9,999 individuals which has a source water annual average TOC level, before any treatment, <= 4.0 mg/L

TTHM annual average <= 0.040 mg/L and HAA5 annual average <= 0.030 mg/L

One sample per treatment plant per year at distribution system location reflecting maximum residence time during month of warmest water temperature. NOTE: Any public water system using surface water or ground water under the direct influence of surface water serving fewer than 500 individuals may not reduce its monitoring to less than one sample per treatment plant per year

System using only ground water not under direct influence of surface water using chemical disinfectant and serving at least 10,000 individuals

TTHM annual average <= 0.040 mg/L and HAA5 annual average <= 0.030 mg/L

One sample per treatment plant per year at distribution system location reflecting maximum residence time during month of warmest water temperature

System using only ground water not under direct influence of surface water using chemical disinfectant and serving fewer than 10,000 individuals

TTHM annual average <= 0.040 mg/L and HAA5 annual average <= 0.030 mg/L for two consecutive years OR TTHM annual average <= 0.020 mg/L and HAA5 annual average <= 0.015 mg/L for one year

One sample per treatment plant per three year monitoring cycle at distribution system location reflecting maximum residence time during month of warmest water temperature, with the three-year cycle beginning on January 1 following quarter in which system qualifies for reduced monitoring

c. Monitoring Requirements for Source Water TOC: In order to qualify for reduced monitoring for TTHMs and HAA5s under 179 NAC 16-005.02 item 1.b., systems using surface water and ground water under the direct influence of surface water not monitoring under 179 NAC 16-005.04 must take monthly TOC samples every 30 days at a location prior to any treatment. In addition to meeting other criteria for reduced monitoring in 179 NAC 16-005.02 item 1.b., the source water TOC running annual average must be <= 4.0 mg/L (based on the most recent four quarters of monitoring) on a continuing basis at each treatment plant to reduce or remain on reduced monitoring for TTHMs and HAA5s. Once qualified for reduced monitoring for TTHMs and HAA5s under 179 NAC 16-005.02 item 1.b., a system may reduce source water TOC monitoring to quarterly TOC samples taken every 90 days at a location prior to any treatment.

d. Systems on a reduced monitoring schedule may remain on that reduced schedule as long as the average of all samples taken in the year (for systems which must monitor quarterly) or the result of the sample (for systems which must monitor no more frequently than annually) is no more than 0.060 mg/L and 0.045 mg/L for TTHMs and HAA5, respectively. Systems that do not meet these levels must resume monitoring at the frequency identified in 179 NAC 16-005.02 item 1.a. (minimum monitoring frequency column) in the quarter immediately following the monitoring period in which the system exceeds 0.060 mg/L or 0.045 mg/L for TTHMs and HAA5, respectively. For systems using only ground water not under the direct influence of surface water and serving fewer than 10,000 individuals, if either the TTHM annual average is > 0.080 mg/L or the HAA5 annual average is > 0.060 mg/L, the system must go to the increased monitoring identified in 179 NAC 16-005.02 item 1.a. (sample location column) in the quarter immediately following the monitoring period in which the system exceeds 0.080 mg/L or 0.060 mg/L for TTHMs or HAA5, respectively.

e. Systems on increased monitoring may return to routine monitoring if, after at least one year of monitoring their TTHM annual average is <= 0.060 mg/L and their HAA5 annual average is <= 0.045 mg/L.

f. The Department may return a system to routine monitoring at the Department's discretion.

2. Chlorite: Community and non-transient non-community water systems using chlorine dioxide, for disinfection or oxidation, must conduct monitoring for chlorite.
a. Routine Monitoring
(1) Daily Monitoring: Systems must take daily samples at the entrance to the distribution system. For any daily sample that exceeds the chlorite MCL, the system must take additional samples in the distribution system the following day at the locations required by 179 NAC 16-005.02 item 2.b., in addition to the sample required at the entrance to the distribution system.

(2) Monthly Monitoring: Systems must take a three-sample set each month in the distribution system. The system must take one sample at each of the following locations: near the first customer, at a location representative of average residence time, and at a location reflecting maximum residence time in the distribution system. Any additional routine sampling must be conducted in the same manner (as three-sample sets, at the specified locations). The system may use the results of additional monitoring conducted under 179 NAC 16-005.02 item 2.b. to meet the requirement for monitoring in this paragraph.

b. Additional Monitoring: On each day following a routine sample monitoring result that exceeds the chlorite MCL at the entrance to the distribution system, the system is required to take three chlorite distribution system samples at the following locations: as close to the first customer as possible, in a location representative of average residence time, and as close to the end of the distribution system as possible (reflecting maximum residence time in the distribution system).

c. Reduced monitoring
(1) Chlorite monitoring at the entrance to the distribution system required by 179 NAC 16-005.02 item 2.a.(1) may not be reduced.

(2) Chlorite monitoring in the distribution system required by 179 NAC 16-005.02 item 2.a.(2) may be reduced to one three-sample set per quarter after one year of monitoring where no individual chlorite sample taken in the distribution system under 179 NAC 16-005.02 item 2.a.(2) has exceeded the chlorite MCL and the system has not been required to conduct monitoring under 179 NAC 16-005.02 item 2.b. The system may remain on the reduced monitoring schedule until either any of the three individual chlorite samples taken quarterly in the distribution system under 179 NAC 16-005.02 item 2.a.(2) exceeds the chlorite MCL or the system is required to conduct monitoring under 179 NAC 16-005.02 item 2.b., at which time the system must revert to routine monitoring.

3. Bromate
a. Routine Monitoring: Community and non-transient non-community systems using ozone, for disinfection or oxidation, must take one sample per month for each treatment plant in the system using ozone. Systems must take samples monthly at the entrance to the distribution system while the ozonation system is operating under normal conditions.

b. Reduced Monitoring
(1) A system required to analyze for bromate may reduce monitoring from monthly to quarterly, if the system's running annual average bromate concentration is <= 0.0025 mg/L based on monthly bromate measurements under 179 NAC 16-005.02 item 3.a. for the most recent four quarters, with samples analyzed using Method 317.0 Revision 2.0, 326.0321.8, 301.0 or 557. If a system has qualified for reduced bromate monitoring under 179 NAC 16-005.02 item 3.b.(1), that system may remain on reduced monitoring as long as the running annual average of quarterly bromate samples <= 0.0025 mg/L based on samples analyzed using Method 317.0 Revision 2.0, 326.0, 321.8, 301.0 or 557. If the running annual average bromate concentration is > 0.0025 mg/L, the system must resume routine monitoring required by 179 NAC 16-005.02 item 3.a.

005.03 Monitoring Requirements for Disinfectant Residuals

1. Chlorine and Chloramines
a. Routine Monitoring: Through March 31, 2016, community and non-transient non-community water systems that use chlorine or chloramines must measure the residual disinfectant level in the distribution system at the same point in the distribution system and at the same time as total coliforms (routine, repeat, and additionals, but not specials) are sampled, as specified in 179 NAC 3-004. Beginning April 1, 2016, community and non-transient non-community water systems that use chlorine or chloramines must measure the residual disinfectant level in the distribution system at the same point in the distribution system and at the same time as total coliforms are sampled, as specified in 179 NAC 26-006 through 26-009. Public water systems using surface water or ground water under the direct influence of surface water may use the results of residual disinfectant concentration sampling conducted under 179 NAC 13-007.02F1 for unfiltered systems or 179 NAC 13-007.03C for systems which filter, in lieu of taking separate samples.

b. Reduced Monitoring: Monitoring may not be reduced.

2. Chlorine Dioxide
a. Routine Monitoring: Community, non-transient non-community, and transient non-community water systems that use chlorine dioxide for disinfection or oxidation must take daily samples at the entrance to the distribution system. For any daily sample that exceeds the MRDL, the system must take samples in the distribution system the following day at the locations required by 179 NAC 16-005.03 item 2.b. in addition to the sample required at the entrance to the distribution system.

b. Additional Monitoring: On each day following a routine sample monitoring result that exceeds the MRDL, the system is required to take three chlorine dioxide distribution system samples. If chlorine dioxide or chloramines are used to maintain a disinfectant residual in the distribution system, or if chlorine is used to maintain a disinfectant residual in the distribution system and there are no disinfection addition points after the entrance to the distribution system (i.e., no booster chlorination), the system must take three samples as close to the first customer as possible, at intervals of at least six hours. If chlorine is used to maintain a disinfectant residual in the distribution system and there are one or more disinfection addition points after the entrance to the distribution system (i.e., booster chlorination), the system must take one sample at each of the following locations: as close to the first customer as possible, in a location representative of average residence time, and as close to the end of the distribution system as possible (reflecting maximum residence time in the distribution system).

c. Reduced Monitoring: Chlorine dioxide monitoring may not be reduced.

005.04 Monitoring Requirements for Disinfection Byproduct Precursors (DBPP)

1. Routine Monitoring: Public water systems using surface water or ground water under the direct influence of surface water which use conventional filtration treatment as defined in 179 NAC 13-002 must monitor each treatment plant for TOC no later than the point of combined filter effluent turbidity monitoring and representative of the treated water. All systems required to monitor under this paragraph must also monitor for TOC in the source water prior to any treatment at the same time as monitoring for TOC in the treated water. These samples (source water and treated water) are referred to as paired samples. At the same time as the source water sample is taken, all systems must monitor for alkalinity in the source water prior to any treatment. Systems must take one paired sample and one source water alkalinity sample per month per plant at a time representative of normal operating conditions and influent water quality.

2. Reduced Monitoring: Public water systems using surface water or ground water under the direct influence of surface water with an average treated water TOC of less than 2.0 mg/L for two consecutive years, or less than 1.0 mg/L for one year, may reduce monitoring for both TOC and alkalinity to one paired sample and one source water alkalinity sample per plant per quarter. The system must revert to routine monitoring in the month following the quarter when the annual average treated water TOC >= 2.0 mg/L.

005.05 Bromide

Systems required to analyze for bromate may reduce bromate monitoring from monthly to once per quarter, if the system demonstrates that the average source water bromide concentration is less than 0.05 mg/L based upon representative monthly measurements for one year. The system must continue bromide monitoring to remain on reduced bromate monitoring.

005.06 Monitoring Plans

Each system required to monitor under 179 NAC 16 must develop and implement a monitoring plan. The system must maintain the plan and make it available for inspection by the Department and the general public no later than 30 days following the applicable compliance dates specified in 179 NAC 16-001.01. All public water systems using surface water or ground water under the direct influence of surface water serving more than 3300 people must submit a copy of the monitoring plan to the Department no later than the date of the first report required under 179 NAC 16-007. The Department may also require the plan to be submitted by any other system. After review, the Department may require changes in any plan elements. The plan must include at least the following elements.

1. Specific locations and schedules for collecting samples for any parameters included in 179 NAC 16.

2. How the system will calculate compliance with MCLs, MRDLs, and treatment techniques.

3. If approved for monitoring as a consecutive system, or if providing water to a consecutive system, under the provisions of 179 NAC 3-010, the sampling plan must reflect the entire distribution system.

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